This invention relates to coupling systems for railway vehicles and in particular to a novel and improved system that provides isolation of the electric and pneumatic lines of a vehicle from its corresponding electric and/or pneumatic intervehicle coupling elements as well as from its corresponding battery when required.
Such isolation is required, for example, when the vehicle is uncoupled and/or during coupling and/or uncoupling operations. Isolation may also be required between an onboard battery and a particular circuit line when such circuit line is involved in a train line loop test.
A typical prior art coupling system is the H2C unit of WABCO, Inc. of Wilmerding, Pennsylvania. In this unit, corresponding electric pin connectors of two vehicles are brought into mating electric contact while hot (connected to a source of electric energy). That is, supply voltages and/or signal conditions are actually present on th connectors of one or both of the vehicles. This results in electric arcs across the connectors as they engage during the coupling process or disengage during the decoupling process. The arcs will result in reduced life of the electric interface connectors.
Particularly troublesome in the H2C unit are the battery voltage connectors. Should a vehicle with a live battery to be coupled to a vehicle with a dead battery, the live battery will try to charge the dead battery. This results in a current draw in excess of 75 amperes through the coupler contacts, which if continued for any length of time can result in damage to the coupler contacts. The only way to stop this condition is to uncouple the vehicles or retract the electric coupler portions.
Another prior art coupling system is the Form 73 Coupler Equipment of Ohio Brass Co. of Mansfield, Ohio. This system includes a control mechanism that serves to isolate the electric and pneumatic lines of a vehicle from its corresponding electric and pneumatic interfaces when the vehicle is uncoupled. During a coupling operation the electric coupling contacts upon engagement initiate a coupling cycle. This action causes an electric signal to be generated that, after a three second delay to assure against false signals, is operative to couple the vehicle electric and pneumatic lines to the vehicle's electric and pneumatic interfaces. A problem with the Form 73 Coupler Equipment is that the interface connector associated with the onboard battery power is hot at the time the two electric interfaces come into electric engagement. This results in voltage arcs and, hence, reduced contact life.
A requirement for coupling systems is that the onboard battery be isolated from onboard electric circuits when the vehicle is uncoupled. This has been achieved in the above prior art couplers by routing battery power across the electric interface, through a loop on the adjacent vehicle and then back through the interface. This required a dedication of at least four connectors per electric interface in the Form 73 Coupler Equipment.